Lubrication system for hammer tool

ABSTRACT

An electric paving breaker is described which includes an electric motor, a crank and a piston driven by the motor, and a ram driven by the piston which delivers energy to a tool bit to produce a hammering output. An improved lubricating system for the rotating mechanism is described.

United States Patent [191 Sides [11] 3,822,001 July 2,1974

[ LUBRICATION SYSTEM FOR HAMMER TOOL [75] Inventor: Daniel Harrison Sides, New

Freedom, Pa.

[73] Assignee: The Black and Decker Manufacturing Company, Towson, Md.

[22] Filed: Mar. 19, 1973 [21] Appl. No.: 342,864

[52] US. Cl. .1. 184/10, 184/102, 308/3 CH [51] Int. Cl. F1611 31/02 [58] Field 01 Search 184/17, 5, 10,63, 101,

[5 61 References Cited 4 UNITED STATES PATENTS 1,661,790 3/1928 Crawford 308/3 CH 1 2,878,896 Farrell 184/105 B 3,029,510 4/1962 Marden, Jr. 30/123 3,119,461 1/1964 Enders 184/5 3,146,856 9/1964 Enders 184/102 3,162,268 12/1964 Short 184/102 X Primary Examiner-Manuel A. Antonakas ABSTRACT An electric paving breaker is described which includes an electric motor, a crank and a piston driven by the motor, and a ram driven by the piston which delivers energy to a tool bit to produce a hammering output. An improved lubricating system for the rotating mechanism is described.

10 Claims, 4 Drawing Figures r 1 LUBRICATION SYSTEM FOR HAMMER TOOL The present invention is directed to heavy-duty power tools of the type used as paving breakers and for other demolition work, and is specifically directed to an improved lubricating system for such tools.

Lubrication in tools of this sort is particularly demanding in that the tools are usually usedunder heavyload conditions and for long periods of time. It is, therefore, necessary that the lubrication system be capable of supplying adequate lubrication to meet these conditions. In addition, it is necessary that the lubricant in the system lasts for an extended period of time so that constant replenishment is not required, and also that replenishment be reasonably easy when it is required. Finally, the lubrication system should be as inexpensive as possible so that it does not add unnecessarily to the high cost of the mechanism.

It is accordingly an object of the present invention to provide a new and improved lubrication system for heavy-duty power tools, particularly those including percussive hammering mechanisms.

A further object of the present invention is the provision of a new and improved lubrication system for power hammers which will supply a metered quantity of lubricant to the mechanism for an extended period of time without replenishment.

Further objects and advantages of this invention will become apparent as the description and illustration there of proceed.

IN THE DRAWINGS FIG. I is an elevational view of an electric paving breaker including a lubricating system in accord with the present invention;

FIG. 2 is a cross sectional view of a portion of the internal mechanism of the paving breaker of FIG. 1, which illustrates a lubricating system in accord with this invention; I

FIG. 3 is a detailed view taken along the lines 33 of FIG. 2; and

FIG. 4 is an enlarged view of a portion of FIG. 2.

FIG. 1 illustrates generally an electric paving breaker in accord with the present invention. The paving breaker includes a motor housing 11 and a transmission housing 12. A motor within the motor housing drives the transmission, which, in turn, rcciprocates a piston in a barrel 13. Reciprocation of the piston causes corresponding reciprocation of a ram which ultimately produces hammer blows on an output member such as a chisel bit 14' which is retained on the paving breaker by means of a tool bit retainer 15. The complete internal mechanism of this particular tool is shown in my copending application, Ser. No. 7336, the specification of which is incorporated herein by reference.

FIG. 2 illustrates the upper portion of the tool of FIG.

1 and specifically shows a vertical cross section through the transmission of the tool. The motor, not shown, terminates in a pinion gear 16 which drives an intermediate gear 17, supported in bearings 18 and 19..The gear 17 is drivingly connected with an intermediate pinion 20 which, in turn, drives a crank gear 2]. The crank gear is connected to a crank 22 and the combination is supported in bearings 23 and 24. The crank includes an eccentric journal portion 25 which supports a bearing 26. A connecting rod 27 is mounted on the bearing, via cap 28 and screws 29 as shown in FIG. 3. The eccentrically mounted connecting rod converts the rotary motion of the crank into linear motion of a piston which, in turn, drives a ram and the bit as is shown in the above mentioned co-pending application.

As previously noted, paving breakers are subjected to heavy-duty use, often for long, continuous time periods. Accordingly, it is of critical importance that adequate lubrication be supplied to the rotating and reciprocating mechanism just described. It is also of importance that the tool contain a sufficient quantity of lubricant so that the operator can, if necessary, operate the tool for many hours without being required to stop frequently to add lubricant or risk damaging the mechanism. Previous tools of this type have often been inadequate in this respect either because insufficient lubricant was provided in the operating mechanism or because the lubricant entered the transmission housing too easily and thus quickly depleted the reservoir. The present invention is directed to an improved lubricating system which overcomes these deficiencies and which provides several significant advantages.

To accomplish these objectives in accord with the present invention, the transmission housing 12 includes a reservoir 30 in one side wall 31. The reservoir 30 is filled with grease and closed by a cover plate 32, held in place by a screw 33. Also within the reservoir is a spring 34 and a spherical ball 35, the spring being arranged to bias the ball tightly-against an opening in the cover plate 32.

in accord with a particular feature of the present invention, a grease filling fitting 36 :is provided, screwed into an opening 37 in the side wall 31. The fitting 36 includes an internal passageway in which are located a spring 38 and a ball closure 39. The fitting is adapted to receive a grease gun, thus enabling the reservoir 30 to be filled from a pressurized source of grease.

In further accord with the present invention, the eccentric 25 of the crank includes an opening within which is placed a porous, felt wiper 40, the wiper being biased outwardly from the eccentric toward the reservoir by a spring 41.

FIG. 3 illustrates a cross-sectional view through this region. As can be seen therein, the: felt wiper 40 is centrally disposed within the eccentric 25. The counterweight 42 which is a part-of the crank can also be seen in this figure. Thus, as the crank is rotated about its axis, the eccentric travels in a circle and, once during each revolution, the wiper 40 contacts the ball 35. FIG. 4 is an enlarged view of the wiper and ball during this contact. As can be seen therein, the ball is lifted by the wiper against the force of spring 34, leaving a gap 43. At the same time, the wiper 40 rotates the ball. During most of the revolution, the portion of the ball which is internal to the reservoir is in contact with the grease. When the ball is rotated, a new surface is exposed to the wiper; this surface carries grease out of the reservoir which is then wiped onto the wiper 40. However, due to the fact that grease is a semi-solid mixture of oil and soap rather than a fluid, no leakage occurs andthe only grease transmitted to the wiper is that carried by the surface of the ball.

Thus, the system just described accomplishes a precise, metered delivery of a very small quantity of grease to the wiper during each revolution. The relative sizes of the parts and the specific grease mixture are, of course, selected so that the delivery of this quantity during each revolution builds up and maintains sufficient lubrication in the transmission housing. As the grease accumulates on the wiper, during the several hundred revolutions per minute made by the crank, it is thrown from the wiper and distributed throughout this housing. The grease adequately supplies both of the bearings 23 and 24 in which the crank rotates, the bearing 26 on which the connecting rod rotates, and also travels down the internal walls of the cylinder 13 to lubricate the area where the piston and other moving parts in the barrel travel. The gears 20 and 21 are also lubricated in this manner. The gears 16 and 17, in the particular embodiment shown, operate in a sealed chamber with a separate lubricant; however, these gears could also be lubricated from the reservoir 30 if appropriate.

As the tool is used, the grease is gradually lost, particularly down the barrel l3, and to maintain adequate lubrication of all of these parts, a continued supply from the reservoir is necessary. In actual use, this system has been found to provide adequate lubrication for periods of use as long as 20 to 30 hours or more. This is in contrast to previous tools of this type which have required lubrication every two to three hours in some cases.

While a specific embodiment of this invention has,

i for convenience, been illustrated and described, it will be clear to those skilled in the art that many changes and modifications can be made therein while still utilizing the basic teaching of this invention. For example, other systems could be easily devised which would make use of the basic concept of a movable surface presented to a semi-solid lubricant in a reservoir and then shifted out periodically to transfer lubricant to one or more wipers located on the rotating crank. Similarly, other fittings designed for use with pressure lubricant supplies could be utilized as the filling means without reducing the simplicity and convenience provided by this aspect of the invention. It is, therefore, intended that the appended claims cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. In a portable, power-operated impact tool of the type including a motor, a crank driven. by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising:

a reservoir disposed adjacent the path of movement of said eccentric;

grease in said reservoir;

an opening in said reservoir adjacent said path of said eccentric;

a rotatable member normally biased to close said opening; and

wiper means on said crank for periodically rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said grease to said wiper means.

2. An impact tool as claimed in claim 1 wherein said rotatable member comprises a ball.

3. In a portable, power-operated impact tool of the type including a motor, a crank driven by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising:

a reservoir disposed adjacent the path of movement of said eccentric;

grease in said reservoir;

an opening in said reservoir adjacent said path of said eccentric;

a rotatable member normally biased to close said opening, said member protruding slightly out of said reservoir toward said eccentric; and

wiper means on said crank for periodically depressing and rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said grease to said wiper means.

4. In a portable, power-operated impact tool of the type including a motor, a crank driven by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising:

a reservoir disposed adjacent the path of movement of said eccentric;

grease in said reservoir;

an opening in said reservoir adjacent said path of said eccentric;

a rotatable member normally biased to close said opening; and

wiper means on said crank for periodically rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said grease to said wiper means;

said wiper means comprising a porous body mounted on said crank for collecting said grease from said rotatable member by wiping, said grease being distributed from said wiper means during rotation of said crank.

5. An impact tool as claimed in claim 4 wherein said porous body is disposed in and protrudes from said eccentric; and wherein resilient means are provided to bias said body outwardly from said eccentric.

6. An impact tool as claimed in claim 5 wherein said eccentric includes a bearing supporting said connecting rod and wherein a passage is provided between said porous body and. the inner surface of said bearing.

7. In a portable, power-operated impact tool of the type including a motor, a crank driven by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising:

a reservoir disposed adjacent the path of movement of said eccentric;

a lubricant in said reservoir;

an opening in said reservoir adjacent said path of said eccentric;

a rotatable member normally biased to close said opening, said member protruding slightly out of said reservoir toward said eccentric; and

wiper means on said crank for periodically depressing and rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said lubricant to said wiper means; and

said wiper means comprising a porous body mounted on said crank for collecting said lubricant from said rotatable member by wiping, said lubricant being distributed from said wiper means during rotation of said crank.

8. An impact tool as claimed in claim 7 wherein said porous body extends above the surface of said crank; said body being positioned to depress and rotate said rotatable member once in each revolution of said crank.

9. An impact tool as claimed in claim 8 wherein a filling means is provided for said reservoir, said filling means comprising means for filling said reservoir from a pressurized source of said lubricant, said filling means comprising an externally protruding nipple having a passageway therein, a seal normally positioned to close the entrance .of said passageway, and resilient means biasing. said seal into passage-closing position.

10. In a portable, power-operated impact tool of the pacts to an output bit; an improved lubrication means comprising:

a reservoir disposed adjacent the path of movement of said eccentric;

a semi-solid lubricant in said reservoir;

an opening in said reservoir adjacent said path of said eccentric;

a rotatable member normally biasedto close said opening;

wiper means on said crank for periodically rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said lubricant to said wiper means;

means for filling said reservoir from a pressurized source of said lubricant, said filling means comprising an externally protruding nipple having a passageway therein, a seal normally positioned to close the entrance of said passageway, and resilient means biasing said seal into passage-closing posi- 

1. In a portable, power-operated impact tool of the type including a motor, a crank driven by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising: a reservoir disposed adjacent the path of movement of said eccentric; grease in said reservoir; an opening in said reservoir adjacent said path of said eccentric; a rotatable member normally biased to close said opening; and wiper means on said crank for periodically rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said grease to said wiper means.
 2. An impact tool as claimed in claim 1 wherein said rotatable member comprises a ball.
 3. In a portable, power-operated impact tool of the type including a motor, a crank driven by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising: a reservoir disposed adjacent the path of movement of said eccentric; grease in said reservoir; an opening in said reservoir adjacent said path of said eccentric; a rotatable member normally biased to close said opening, said member protruding slightly out of said reservoir toward said eccentric; and wiper means on said crank for periodically depressing and rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said grease to said wiper means.
 4. In a portable, power-operated impact tool of the type including a motor, a crank driven by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising: a reservoir disposed adjacent the path of movement of said eccentric; grease in said reservoir; an opening in said reservoir adjacent said path of said eccentric; a rotatable member normally biased to close said opening; and wiper means on said crank for periodically rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said grease to said wiper means; said wiper means comprising a porous body mounted on said crank for collecting said grease from said rotatable member by wiping, said grease being distributed from said wiper means during rotation of said crank.
 5. An impact tool as claimed in claim 4 wherein said porous body is disposed in and protrudes from said eccentric; and wherein resilient means are provided to bias said body outwardly from said eccentric.
 6. An impact tool as claimed in claim 5 wherein said eccentric includes a bearing supporting said connecting rod and wherein a passage is provided between said porous body and the inner surface of said bearing.
 7. In a portable, power-operated impact tool of the type including a motor, a crank driven by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising: a reservoir disposed adjacent the path of movement of said eccentric; a lubricant in said reservoir; an opening in said reservoir adjacent said path of said eccentric; a rotatable member normally biased to close said opening, said member protruding slightly out of said reservoir toward said eccentric; and wiper means on said crank for periodically depressing and rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said lubricant to said wiper means; and said wiper means comprising a porous body mounted on said crank for collecting said lubricant from said rotatable member by wiping, said lubricant being distributed from said wiper means during rotation of said crank.
 8. An impact tool as claimed in claim 7 wherein said porous body extends above the surface of said crank; said body being positioned to depress and rotate said rotatable member once in each revolution of said crank.
 9. An impact tool as claimed in claim 8 wherein a filling means is provided for said reservoir, said filling means comprising means for filling said reservoir from a pressurized source of said lubricant, said filling means comprising an externally protruding nipple having a passageway therein, a seal normally positioned to close the entrance of said passageway, and resilient means biasing said seal into passage-closing position.
 10. In a portable, power-operated impact tool of the type including a motor, a crank driven by said motor and including an eccentric; a connecting rod mounted on said eccentric; a piston mounted on said connecting rod; and a ram driven by said piston for delivering impacts to an output bit; an improved lubrication means comprising: a reservoir disposed adjacent the path of movement of said eccentric; a semi-solid lubricant in said reservoir; an opening in said reservoir adjacent said path of said eccentric; a rotatable member normally biased to close said opening; wiper means on said crank for periodically rotating said rotatable member upon revolution of said crank whereby each periodic rotation of said rotatable member delivers a quantity of said lubricant to said wiper means; means for filling said reservoir from a pressurized source of said lubricant, said filling means comprising an externally protruding nipple having a passageway therein, a seal normally positioned to close the entrance of said passageway, and resilient means biasing said seal into passage-closing position. 